Existing strippable coating systems generally use an intermediate coating between the primer and the top coat. One type of intermediate coating, described in GB-A-1511935, is a non-crosslinked polyamide. This at least partially resists the solvent used to remove the top coat and can itself easily be removed by alcohol-based solvents to reveal the primer. Similarly, DE-A-2528943 describes a linear non-crosslinked elastic polyurethane coating used between crosslinked polyurethane primer and top coat layers. EP-A-147984 describes a barrier intermediate coating comprising a film-forming addition polymer comprising units of a vinyl aromatic monomer and units of a monomer containing a hydroxy alkyl group in an amount to provide a hydroxyl content of the addition polymer in the range 0.5 to 5 per cent by weight reacted with a polyisocyanate containing at least 2 isocyanate groups per molecule.
All these prior art intermediate coatings are based on solutions of synthetic resins in organic solvents. There has been a demand for an intermediate coating which releases less, preferably no, volatile organic solvent.